Résumé
Landraces are valuable sources of genetic diversity for addressing the challenges of climate change, reducing fertilizers and pesticides but remain underutilized in modern breeding programs. To fill this gap, the MineLandDiv project (Mining Allelic Diversity in Landraces for Tolerance to Abiotic and Biotic stress) aims at (i) identifying maize landraces and favorable alleles for tolerance to abiotic (heat/drought - cold - nitrogen) and biotic stresses (Corn borer) that could be used to broaden genetic diversity of modern breeding germplasms and (ii) better understanding their resilience to variable environmental conditions. We optimized a panel of 341 temperate maize landraces representative of European genetic diversity that we evaluated for roots architecture in platform and for various agronomic and physiological traits across a field trial European network of 6 locations using high troughput phenotyping / envirotyping tools. We observed a strong effect of stress for yield according to treatments and environments. We genotyped DNA pools of these landraces with 600 000 SNPs to conduct genome wide association studies with traits and environmental variables from landrace collecting sites. We identified genomic regions involved in trait and environmental variation. We developed a DNA pool targeted sequencing approach to compare haplotype contents at 14 genomic regions involved in tolerance to abiotic stresses using 372 landraces and 342 inbred lines. We showed that 17% of genetic diversity found in landraces has been lost in inbred lines. We developed genomic prediction that predicted with high accuracy agronomic traits in different environments. First results are encouraging to identify promising alleles and landraces for prebreeding.